Engines, including diesel engines, gasoline engines, gaseous fuel powered engines, and other combustion engines exhaust gasses having a complex mixture of air pollutants. These pollutants include, among other things, solid material known as particulate matter or soot. Due to increased attention on the environment, exhaust emission standards have become more stringent, and the amount of particulate matter emitted from an engine is regulated depending on the type of engine, size of engine, and/or class of engine.
Exhaust systems have been developed to manage the exhaust gases from combustion engines. Exhaust systems usually include a conduit that directs the exhaust gases away from the engine for subsequent treatment by various devices. The devices include, for example, a diesel particulate filter (DPF) to trap the particulate matter, and a regeneration device, such as a burner, to periodically regenerate the DPF. Other devices, such as turbochargers that use the exhaust gases to generate auxiliary power, can also be included. Exhaust systems are sometimes equipped with temperature and pressure sensors to monitor the temperature and pressure of the exhaust gases at various points. The monitored temperatures and pressures are used for diagnostic and control purposes, e.g., to verify compliance with regulations and/or to control regeneration of the DPF.
One method of diagnosing exhaust system performance is described in U.S. Patent Application Publication No. 2007/0101699 by McNulty et al. published on May 10, 2007 (the “'699 publication”). The '699 publication discloses a system that compares temperatures measured by adjacent temperature sensors in an exhaust system to determine whether one of the sensors is “stuck within range” prior to performing an exhaust system diagnostic test to ensure the results of the test are meaningful.
Although the system of the '699 publication may improve the results of exhaust system diagnostic tests in some cases, it may be unreliable. For instance, the system only determines whether the temperature sensors are “stuck within range.” The system may not identify a malfunctioning sensor which, although not “stuck within range” (i.e., not stuck at a specific value), provides an inaccurate or inaccurate reading of its respective temperature. The results of a subsequent exhaust system diagnostic test may thus be fouled. In addition, the exhaust system could be compromised by continuing operation with temperature sensors in this condition.
This disclosure is directed to overcoming one or more of the problems set forth above.